Tutorial: Quantum Information & Cold Atoms

2. Purifying EPR pairs
• A noisy quantum channel allows us to generate many noisy EPR pairs.
1/2 < F < 1
...
Bennett et al., Deutsch et al. PRL '95
purification
F ~ 1
If F 1/2 we can purify and obtain one EPR pair with F 1.
To do this we need a small quantum computer.
• In summary: quantum communication via a noisy channel:
- we generate one high fidelity EPR pair by purification
- we teleport the quantum state
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